In a principal aspect the present invention relates to a direct current circuit, digital display and polarity testing device.
Mechanics and technicians often need to determine the polarity as well as the voltage associated with direct current circuits. Typically, the voltage of such circuits is in the range of up to 60 volts D.C. That is, computers and other devices associated with automotive and mechanical sensors and controls are generally part of lower voltage systems. As such, auto mechanics, technicians such as computer technicians and others that service control systems and mechanical devices, may desire to validate the magnitude of the direct current voltage as well as the polarity of devices that require service.
Various prior art devices have thus been developed which enable technicians and mechanics to measure polarity and/or voltage magnitude. Liquid crystal diodes are often incorporated in such test devices to visually indicate voltage of a particular system or device or circuit. Polarity is often determined by separate testing devices. Test equipment which measures voltage over a range and which may enable determination of polarity of a circuit have also been developed. Such devices, introduced into the marketplace, provide visual readout of voltage as well as visual indication of the polarity of a contact in a circuit. Thus, various types of digital display, direct current, circuit testers have been developed and introduced into the marketplace. Following is a listing of prior art patents directed to such technology: